Engineering Application of Miniature Specimen Sampling Method on FFS Assessment of Corrosive Pits of In-Service Pressure Pipeline

2018 ◽  
Author(s):  
Yuqing Yang ◽  
Xin Du ◽  
Ting Zhang ◽  
Hu Hui ◽  
Yichang Huang ◽  
...  
Keyword(s):  
Sampling Method ◽  
Engineering Application ◽  
Test Method ◽  
Small Punch Test ◽  
Periodic Inspection ◽  
Punch Test ◽  
Miniature Specimen ◽  
Pressure Pipeline ◽  
Service Inspection ◽  
Specimen Sampling

This paper aims at in-service inspection of a petrochemical companies’ process pipeline which was found to have corrosive pits during a regular periodic inspection. By adopting miniature specimen sampling method, some (size of 12 × 12 × 1.3mm) sheets were obtained in the pipeline. Yield strength and tensile strength of the material can be obtained by small punch test method. Fitness-For-Service (FFS) procedures based on different standards are performed on the corrosive pits and the sampling areas to assess their safety. The research shows that it is feasible to obtain the actual mechanical properties of the material in the field by using the miniature specimen sampling method. The method mentioned in this paper is of guiding significance for FFS assessment on in-service pressure pipelines.

Study of Fatigue Properties of Materials through Cyclic Automated Ball Indentation and Cyclic Small Punch Test Methods

2017 ◽  
Vol 734 ◽  
pp. 273-284 ◽  
Author(s):  
Raghu V. Prakash
Keyword(s):  
Fatigue Property ◽  
Test Method ◽  
Life Assessment ◽  
Remaining Life ◽  
Small Punch Test ◽  
Small Punch ◽  
Punch Test ◽  
Ball Indentation ◽  
Fatigue Data ◽  
Cycles To Failure

One of the important inputs while estimating the remaining life of critical components is the fatigue property of materials. Fatigue data, in the form of stress vs. cycles to failure (or) strain vs. cycles to failure (or) fatigue crack growth rate data is used to predict the residual life. Material’s fatigue property degrades with time and usage; hence, it is appropriate to use the current properties for remaining life assessment. Often the quantity of material available for generating fatigue data is limited, especially, if the material is scooped out of existing component of a power plant. Further, fatigue response being probabilistic in nature, requires multiple specimens to be tested at any given stress/strain levels. This has prompted us to develop test procedures to determine the fatigue data of materials from a limited volume of material. This paper presents the results of cyclic ball indentation test method as well as cyclic small punch test method that is used to generate the fatigue data at different stress levels. There are several fine details relating to these test techniques – viz., establishing a equivalent damage criteria for failure life with standard LCF/HCF test specimens. The influence of one of the variables, viz., friction at the specimen-tool interface of a small punch test is investigated through numerical simulation and the results are presented here.

Correlation of Tensile Properties of Pressure Vessel Steels by Shear Punch and Small Punch Test Methods

2012 ◽  
Author(s):  
Raghu V. Prakash ◽  
T. Ramesh ◽  
N. Raju ◽  
S. Suresh
Keyword(s):  
Tensile Properties ◽  
Pressure Vessel ◽  
Test Method ◽  
Small Punch Test ◽  
Small Punch ◽  
Punch Test ◽  
Nominal Size ◽  
Shear Punch Test ◽  
Pressure Vessel Steels ◽  
Shear Punch

A shear punch test is a very useful small specimen test method for evaluating the mechanical properties of in-service components, in view of the requirements of small size sample material. Typically disks of nominal size 10 mm diameter, having a thickness of 0.5 mm or less is used to extract the tensile properties through measurement of load-displacement responses. This paper presents the results of shear punch tests on pressure vessel steels and its correlation with yield stress and ultimate tensile stress obtained using ASTM standard specimens. Small punch test is similar to shear punch test, except that the indenter is spherical in shape, and as a consequence the material under the punch will be subjected to biaxial state of stress. The tensile response of materials derived by small punch test is correlated with standard tensile tests.

Small punch test method assessment for the determination of the residual creep life of service exposed components

1999 ◽  
Vol 4 (3-4) ◽  
pp. 283-293 ◽  
Author(s):  
Boris Ule ◽  
Tomaz Sustar ◽  
Tomaz Rodic ◽  
Ferdinand Dobes ◽  
Karel Milicka ◽  
...  
Keyword(s):  
Test Method ◽  
Small Punch Test ◽  
Creep Life ◽  
Small Punch ◽  
Punch Test

Determination of Norton Creep Law From Small Punch Test

2014 ◽  
Author(s):  
Xiangsai Feng ◽  
Yanfeng Qin ◽  
Kai Ma ◽  
Kaishu Guan
Keyword(s):  
Nuclear Power ◽  
Engineering Application ◽  
Small Punch Test ◽  
Creep Tests ◽  
Small Punch ◽  
Code Of Practice ◽  
Punch Test ◽  
Membrane Stretch ◽  
Creep Curves

The present work focused on a miniature test named small punch creep test which have been employed to electric power, petro-chemical, nuclear power and other fields widely in the last three decades. Under normal circumstances, engineering application pay more closer attention to the Norton creep law. To determine the Norton creep law, at least three creep curves were needed by traditional method, it’s time consuming and uneconomic. In present paper, the small punch creep tests were carried out following the CEN code of practice. Based on Chakrabarty’s membrane stretch model and Norton power law, the results of small punch creep tests and finite element method have been compared and discussed. A completely novel and economical approach was proposed to determine the parameters of Norton creep law more accurately and conveniently. The results show that, if scopes of parameters known, the Norton creep law could be determined accurately even from one creep curve only.

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